Hydrosilylation chemistry, involving the reaction between a silylhydride and an unsaturated organic group, is the basis for many addition cured products including sealants, elastomers, RTVs, adhesives, and silicone-based coatings. Addition cured silicone formulations are typically comprised of:                (A) an alkenyl substituted polysiloxane that is the primary component or base polymer of the curable composition;        (B) a hydride functional crosslinking silicone, typically a methyl hydrogen siloxane polymer, copolymer or oligomer;        (C) a highly active addition cure hydrosilylation catalyst, typically a platinum (0) catalyst such as Ashby's or Karstedt's; and        (D) a cure inhibiting compound or mixtures thereof to increase the useful life of the complete formulation.Addition curable silicone formulations of the above composition must have both rapid cure at elevated temperature and an acceptably long working life (i.e., no crosslinking) of the full formulation at room temperature. This need is particularly acute for release coating formulations where perhaps the most stringent demand is placed on the catalyst for extremely fast cure at high line coating speeds and very short oven-dwell times (2-5 seconds), together with good bath life of the formulation. Yet, the formulation must essentially completely cure in seconds at elevated temperature to meet release performance requirements on a plethora of different paper and polymeric substrates. To accommodate these two opposing demands, two part formulations with high platinum loadings and high inhibitor loadings are typically employed in the industry. This current solution has several distinct disadvantages. High platinum catalyst loadings are required in addition curable systems to ensure rapid and complete cure at elevated temperature but this high loading of precious metal catalysts also imparts a significant catalyst cost to the formulation. In addition to cure performance, high platinum catalyst levels are especially needed in release liner applications to ensure adequate anchorage to the substrate. High levels of inhibitors are employed to retard catalyst activity and to extend working life of the formulation at room temperature, but the inhibitors employed may not be rapidly de-complexed from the platinum center at elevated temperature and slow the desired crosslinking reaction at elevated temperature. Lastly, two part formulations require additional time and mixing steps before the use of the formulation.        
Other platinum based catalysts besides the previously mentioned Karstedt's and Ashby's catalysts have been reported. PtCODCl2, PtCODMe2, and PtCODPh2 are commercially available and their use as catalysts for hydrosilylation reactions has been known for many years (JP 54076530A, JP 54076529A, EP 472438, L. Lewis et al., Organometallics, 1991, 10, 3750-3759, and P. Pregosin et al., Organometallics, 1988, 7, 1373-1380). Roy et al. have reported the preparation of a series of PtCOD(SiR3)2 compounds from PtCODCl2 (Roy, Aroop K.; Taylor, Richard B. J. Am Chem. Soc., 2012, 124, 9510-9524; and U.S. Pat. No. 6,605,734), but their use in silicone crosslinking is not reported or indicated. The use of PtCODPh2 has been reported for use in radiation cure systems (WO9210529). Complexes with the general formula PtCOD(alkynyl)2 and Pt(COD)(ureylene) have been cited as catalysts in curable silicone rubber compositions (EP 0994159, U.S. Pat. No. 7,511,110). These complexes, however, suffer from their poor solubility in organic solution and silicone formulations. Chlorinated solvents such as chloroform or dichloromethane are employed to dissolve the catalyst. In addition to health and environmental concerns posed by such chlorinated solvents, they are also highly volatile which poses formulation challenges.
Pt-COD complexes with catecholate or amidophenolate ligands have been reported (Boyer et al. Inorg. Chem 2009, 48, 638-645; Richmond et al, J. Chem. Crystallogr. 1996, 26, 335-340). These papers describe the electronic structure and redox reactivity of these Pt complexes. The use of these platinum-diene complexes with chelating dianions in hydrosilylation reactions has not been reported.
There is a need in the silicone industry for platinum catalysts of improved stability as industry work-horse catalysts such as Speier's and Karstedt's are prone to partial deactivation via agglomeration, especially at elevated temperatures of use. Improved stability of the active catalyst would enable the lowering of Pt catalyst loadings. In addition to improved stability, catalysts that demonstrate rapid activation and high hydrosilylation activity at elevated temperature, but also display a long working life for formulations stored at room temperature at low or no inhibitor loadings are especially sought. Lastly, platinum catalysts are needed that have improved solubility in industrially-preferred organic solvent or silicones. The present invention provides one solution to these needs.